Airplane carrier



Aug. 7, 1945. J. F. H. FEcHTr-:NB'URG 2,381,583

AEROPLANE CARRIER Filed Feb. .28, 1942 6 sheets-sheet 1 Fg $6 Ni m,

o Q o I 0 o N o l y o o J o R4; w 0E o o o io o Q O y o Aug. 7, 1945. J. F. H. FECHTENBURG 2,381,583

ARROPLAN'E CARRIER v Filed Feb. 28, 19212 e sheets-.sheet 2 Aug. 7, 1945. J. F. H.` FECHTENBURG 2,381,583

AEROPLANE CARRIER Filed Feb. 28, 1942 6 Sheets-Sheet 5 Aug. 7, 1945. v J. E. H. FECHTENBURG AEROPLANE CARRIER s snee'ts-sheet 4 Filed Feb. 28, 1942 Aug# 7, 1945. J. F. H. FECHTENBURG AEROPLANE CARRIER 6 Sheets-Sheet Filed Feb. 28, l1942 Aug. 7, 1.945; 1. F. H. FECHTENBURG 2,331,583

AEROPLANE CARRIER 6 Sheets-Sheet mu-Mx A T1-...weissw- Patented Aug. 7, 1945 y untreu .PATENT- omer. i

y y l 2,381,533 Y V CARRIER' Jrgen F.

n. Fechtehhurvg, Cheltenham Township,

yltIontgomery County, Pa;

Applicatiehfr'teheuaiy 2s, 1942, serial No. 432,853

7" claimt (c1. x14-43.5)

fi invention relates .to a vnewv novel'giorrn .of aircraft carrier which-is adaptable foruse as mobile, oishore base for intercepter,

those engaged in coast defense.V v' y v VOne object yof the invention is to provide an aircraft ,carrier whichl will have a minimum deck area exposed to attack from the air, and minimum broadside, bow-and stern exposure to attack by ytorpedoes launched Ifrom air, surface or-fsub-L ,marine'craft or gun-.nreattackfrom hostile ship or shore artillery, While at rthesarne time providing maximum plane-storage'space, and adequate runways for the taking off and ,landing of the planes., Another object of .the inventionnis tolprovde'an Aaircraft carrierfor sea duty which will be capable of extremely'highspeedsand which will be read'- ily maneuverable at highfspeeds', as a [primary means .ofdefense against vattackby enemy4 air, surfacaor submarine craft. f 'y f Another object of the` invention is to providean aircraft carrier of minimum `weight andA Iriarxli-y mumstability which willbe capable of yat,tai`rl i'ng and maintaining speeds comparable lto orgreater,

thahthe landing and ,take-oirspeeds. of modern aircraft of the fighter and light bombing types;

i whereby the aircraft canv take off from, or'land Aon, the4 carrier, whilevthe carrier is under way,

thereby reducing to a minimum the deck areay necessary `for 4such 'purposes,-` vand. makingfava'ilable greaterstorage spacefor planes.,

, Anothercbject of-.the invention is to provider-an aircraft carrierfof a relatively Vsmall size andflcw rcost,y as compared to the large,=expensiverelatively cumbersomeand extremely vulnerable air;-

plane carriers employed bythe naviesofthe varie f vous nations` atthe present time; whereby a com,-

plement of aircraft equal lto or Vgreater,thanr the maximum plane complement'of al large Lmoele'rn aircraft carrier may be divided into a large` number of relatively smally unitsvor squadrons,A each with its ownbase craft, to spread out over ari-area ofthe sea many times as large as `vthe vmaximm'i area which lcould possibly bel covered bythe same number of planes based on andoperating from a I yany building up of the sea in the channel formed byr` and between the spaced hulls; and tomake it possible for the carrier to take on supplies Afrom a submarine, for example, moored to and between the spacedv hulls, whereby, in the vface of anat,- tack yby enemy craft, the Asupply ship may be cut loose quickly, to submerge, and whereby the carrier may make a quick departure from the 'spot ,to foil the attack. If desired, the carrier may act asa base for small submarines or fast surface lcraft of the so-called mosquito type, to operate inconjunction with the planes basedl on the carrier. y

Obviously, the carrier would be'equipped with the necessary anti-aircraft guns, andwith large and small calibre machine guns, strategically lo catedon the superstructure, decks, etch,` for defense purposes. Y 'f y `Inthe accompanying drawings: v

Figs. 1a and lbconstitute Aa plan view of the carrier; A

single large carrier, and atthesame timeymakin'g it impossible yforan enemy. tof. destroy the whole vof thelarge force by concentrated attack on one centralized objective, as ispossible in the caseof the large airplane carriers. y y y. 4, A

Another object o f theinvention is to employ the principles Yof the catamaran in constructing theabase craft lof the` suin-etllitypeY carrier of*` the present invention, with the laterally-spaced hulls Fig. 2 is a port-side View; Fig, 3 is a viewfrom the bow lookingiaft;

Fig. 4 is a view from the stern looking forward; Fig. 5 is a longitudinal-sectional view taken on the' line 5 5, Fig. 3.; 'v j e Fig. 6 is an enlargedcross-sectional view taken on the line 6-6, Fig. lagand l Figs. 7 and 8 are diagrammatic plan views showing modiedforms of the arrangement of the catamaran hulls.

,'Primarily, the base' craft l ycorriprises a pair oflaterally-spaced hulls Ia'and Ib, of which la indicates the port side hull, i. e. the hull at the left side of the craft I when locking toward Vthe bow, `While the starboard hull is indicatedy at Ib.

' The twin hulls, laf-I b, are of similar construction and are held in laterally-spaced parallel relation to each other bya superstructure 2, with a vchannel 3 formed by fand between the two hulls.

The superstructure! primarily comprises, in

the present instance, three transverse bridge structures 2a, 2b and 2c, respectively located at the forward, midship, and after portions of the base craftl., A

4'Ihebridge structures 2a, 2b and 2c are joined together, centrally of the superstructure ,2, by a longitudinal structure 4, and at either side thereof, labove the port hull la and starboard hull lbf, y respectively, by longitudinal stringers 5u. and 5b.

, Carried by the aftbridge r2c', inboard of the base craft `|over'the channel 3, is a plurality of laterallyfspaced high speed' airplane motors', 6a and 6b, of the straight-in-line, V,'or radial type `the present instancearethree y n y I0, Illa,` and Ib, respectively, which loverlri'e the e the carrier is toiuriction as a baserf nach hun; la and legis provided with a rudder CFI 8a or 8b, as the case may be, of sufcient size to effect rapid changes in the course of the` carri-e while the carrier-is traveling at relatively,l high,

speeds, under the impetus of the three aircraft propellers 1, Iaand 1b, in open water.

For harbor and other relatively slow. speedi maneuvering, the hulls la and Ib are ,provided with normal ship propellers 9a. and 9b, respectively, marine engine, preferably Diesels, within the hulls4 Id and Ib, respectively." v

On therupper vsideofmtlie superstructu ,f y airplane ril vways located longitudinal structure 4' and the side stringersfo and 5b. I'hecentral'ru'nway lis at af'sorrnewhat higher elevation than the side runways `Illdfand IDU, for wing-tip clearance for theplane's'on the runways. y M fl The rear end of each runwayis'iiar'ed laterally, to provide a landing deck'l I,1I Iaand I Ibg'asL the case may be, for each runway, with' these llanding decks in overhangin'g relation tothe stern of; he base craft I. If desired, the runways could 1n `a single plane with a single landing deckl stern serving all three runways, y, I,

A plurality ofarplanesl A,`,A are adapted, n rmally, to be parked on the runways I l` fIfl'la';I in spaced relation, in lesma'l and a'wtheach plane locked, lashedo`r otherwise secured''nQv its place on the runway. y', y I

Under the bridge structures 2a, 2lb,-2cand the longitudinal structure II of the superstructure 2, the carrieris provided with atrolley-track ,I2, for` suspending one l,or moreseaplanes B', B inthe air channel I3, located above the'water channel Between towers4 Ida, |417, which form the opposite ends of each of thebridge structures 2o, 12,12 and 2c, the decks I5 a, I5b of the hulls Iaandjlb, respectively, are provided with storagel spaces ifor spareor damaged aircraft C, C. f Q v The planes C,v C-are adapted tobe swunginto and out of the storage spaces on `the'decks ofthe two hulls, to and` from-,the water, or to andffrom the top sideof the superstructure 2*,by any .suitavble derrick or otherhoisting mechanism; etc such, `for examplaas davits` Iter,v IIb having inanual or hydraulically-operated telescoping standards I1a, IIb which are pivoted,` to thejhulls and Ib, respectively,von ,ory Illa, I4b of the-bridge struCturesZaQZb, amilo'.

The seaplanes B, B maybe picked up from the water from within the water channel3,1051,y power driven hoisting mechanism. I 8 carried, for ,example, by trolleys mounted on the trolley-track I2., or by booms on the hulls Ia, and/or Ib at or, adjacent the towers tudinal structure 4as shown inFig. I

Preferably, the bridge ,structures 27a, 2band` 2c, including their end towers` Maand I4b,.and,the longitudinal structure `Mare of hollow-construction of sufoient cross-sectionalI proportions to provide intercommunicating passagewaysvgjfrorn side to side ofA the carrier, acrossthe central chanwhich are driven by any suitable-typeiof rv'control cabin qhousingthe steering and other navigating appal5 and. of high ypower rating, which, in the present nel 3, and from end to end of the carrierv for the personnel of the carrier to pass from one to the other of the hulls Ia and Ib` and from end to end ofthe carrier. The lower portions of the towers Illa and IlIb communicate with the holds of the hulls Ia and Ib, also with the decks of said hulls, and with the cross-structures 2a, 2b and 2c, and are provided with suitable Iadderastairways, etc., for use of the personnel. ,'-flPrefer'ably, the forwardendofg the structure 4, out in front of the bridge `structure 2a, beneath the central runway I0, is extended to provide a 2B for the carrier, with the cabin ratus. `'At` strategic points on the superstructure 2, andgif-:desired along the outside of each' of the l hulls4 Idy and Igb gunplacement bays are provided to house anti-aircra'ft,-machine guns, etc., for

defense 's of the craft against attack. Also, if

desired, the bows of the hulls Ia and IbA may be 'providedwith torpedo tubes and the sternsof the twojhullsr may be equipped jwith apparatus for hurling l or rollin-gy depth-bombs overboard, astern ofthe craft. In the present, instance, the gun placements on the superstructure l2 are indicated at 2l; `the `.gun placementsmalohg the hulls Ia 'and Ib and thoseon or in cthe' towers Illal and Mb arejndi'c'ated at 2Iaf` andZIb; thetorpedo tubes are indicated at 2721.1and 22D; and the depth-bomb dischargersare `indicated at' 23d, and 243D.

1 The personnelmay be quartered in the bridge struoture'sf2.a.,l 2b aindgZ/c," the towers Ma and Mb,

' thelongitudinalpassageway,4,"erin the hulls la the noted, and'thepcarrier is normallydriven `160 adjacent the towers I4a, |417, or in the centralnlongiliand Ib, below deck."

l Obviously, the hullsl Id and Iby will beprovided with storage space yfor supplies,v andainrnunition Asp'areparts ytor, the :planes and' necessary machine- ,shop equipment lfor makingV emergency, repairs to the planes ordtoijthe carrier structure itself, suitable hatcheslanddoorways' being'prov'ided in the decks, of the hulls y Id and Ib5 and in the towers M a and lill) to lprovide forstowing 'supplies in the uns.,

,'When on sea duty, inpatrollirig or in pursuit of enemy craft, the planes A,'V'A,"B,B,` and C, C are' secured in place'4 on the carrierjas previously by some or allof 'its engines f6 and propellers 1. Should eXtra speed be desiredv above ythe'rnaxirnurn affordled'y by thecollective efforts of theI` three vengines 6, 6,' the engines ofl the variousy aircraft may be put into operationto supply additional impelling force by the respective propellers of the airplanes. When ythe time arrives ,for thev airplanes A, A to take to theiair,they speed 'of the carrier as a whole islin'crea'sed 'ordecre'asei asthe case may be, to theproper take- 01T speed of the planes, whererupon the foremost' planes A, A in the files a, al, a2, are` released from" theirv moorings, and the speeds of theirpropellers'increased to providethe necessary speeddifferential, between the forward motion offthe carrier 'and that of the plane, to effect the take-off, it ylosing understood that the forward niotionof the 'carrien as avvhole, simulates the pre-takeeo run `of the airplane normally required for a planeto take-off from ya stationary runway of a flying fielder from the deck oi" the large present-day airplane'carriers.

Inthe above manner, Vthe planes in the various les, cipal land d2 may ftake olf in succession. The seaplanes B, B, under-slung in the air channelv I3may likewisetake Voil? from the'track I2 in succession.

`It is understoodfthat two-,way radio communithereof.. Y y v y. `Vln the case of the seaplanes B, these. would settle l ltionwithinthe channel 3. e l i 'In Iorder to prevent building up. of theA Sea in l the/channellbetween thehullsl'a and Ib, the i" channel3 is entirely free of anyobstructions', such as crosstes. between the v`twoj hulls below Vthe water line, shown in ybroken.lines in Figs.A 3 'and 4, y or at any `elevation between'the keels ofthe Yhulls andthe top decks'la and |5b thereofl which ,are disposed in a' substantially common'plane vat asubstantial heightfabove thewater line, `and both hulls 'arefp'rovi'ydcd' with substantijallyv hat,

cation `would be maintainedbetween A the vcarrier andthe various planes in. flight, thus, when a plane is ordered to land on the carrier, the lfor,-

' ward speed` offthe carriergand that oftheplane are synchronized, while Vthe plane hovers kabove and follows the identicalstraight line course of 'thecarrienwhereupon Athe plane descends gradue ally-from fabovethe carrier'until it makes contact with the landing deck'll, Hq orL I lb, asthe oase may be;` Upon landing; the engine `ofthe pla-ne' is,A kept running tcturn over,the,propellerr at sumf cientspeedfto hold `the planein ,position on the landing desk,I togprevent fthe, carrier from Arunning crew, stationed-alongsuitable cate-walks 26 provided atthe opposite sides of each of the landingdecka and along runways, il desirecl. The r'ground ycrew proceeds to lash the plane in position, afterr whichv the motor of the plane may be Stopped, if desired. i

.The runways l0, lilo, lub, andflandingdecks l I.,

fila snivubtherecf yare provided with sultan@ side guards 24-242to preventvthe planes from e f running -oifthe ysides oftherunways. lioisnightl lthe hull is cut underin a smoothly curvingwater'- slip contour tothe shaft-loger skeg 29 for the propeller shaft' ofthe hull.

The outer side 30 of each 'hull is similarly cut under adjacent the stern to'theshaft-log 'or skeg,

as shown at 3 I. l

The forward portion l,321'of the outer side 3l)y of the hull, in each instance, curves inwardly from the substantially vertical plane of the :midship .portion of said: lside 30 to the' vertical plane of .the inner side 21 of the hull; and'is also cut under in smooth, rounded contour 33 from the horizonv tally square, iiat nose 34 of the bow, at theideck landing, the runway, inunediatelyadiacent these guards-.may be equipped with; spaced lamps 25' projecting beams of light vertically along the sideredges .of the runways to indicatethelocation On the `V'Vaterand `come `to rest while the carrieris maneuvered-into a position to straddle the plane,

uponr thehoisting y apparatus `vI 8 .would be brought yinto operation to hoist Y theplane from v the. water f .into arryinepostion in the au. channel `la 3, v.The,purpose/.of the planes A, as in the `case .of vplanes operating from a large airplanecarrier, is

to intercept enemy bombersand to give battle to lighter ,planesvprotectingl the bombers, `als well as toggattack enemy ships'and-landingparties atv tempting to approach and establish beach-,heads on thegshore,v etc.,l being` defendedfcy theplanes 0f- 4the Carden e' .The primaryvfunction of the seaplanes ,B would battle, although it will beunderstood that thesea` planes vBB as, well .as the airplanes A, `llsniaylce providedwith machine guns,` small cannone'o'r bombs and otherwise equippedto take part-in ,any

ncounter inwhich the y'planes A V may become l involved?, if

As previcuslynnoted, the carrierffmayr'lbe provisioned from a submarine at sea, by the 'carrier running astraddle of the ksubmarine?,which v has come to the surface, with thesubmarine inposivertical, parallel inner vsidesjZl",v ZTeXtending conf tinuo'usly yfromV the sternfto a point a shortv 'di's tanceforwardfof :the stern` of the craft, where tneiqwer stern Portion: 2s ofthe innerside 21, of

l level, tothekeel35,fwith the` forward line ofthe lcow` 36 curving downwardly and 'aftfrom .said deck level to saidlkeel, in the verticalplane of the inner side 21 of each hull.

cThe bottomy 31 ofeachhull ares'upwardly and outwardly from the keel 35, lying in the vertical .plane ofthe inner side -21y ofthe-hull, to the'outer side 30 ofthey hull and curves smoothly into the bow -rand stern undercuts 28 and' 3| previously noted. l *y With the bottoms of thetwo hulls flaring outwardly and upwardly in oppositefdirections from the vertical inner sides 21, 21 of the hulls larand lb,`by which the channel 3 is dened, Aalmodified V bottom craft is provided which, when the craft is'under way, especially at high speed, vcuts and throws the water outwardly -in opposite directions,

away from the channel 3f, and causes .the vhcw portion of each hull to rise in and out of the water.

To'prevent side wash from under they exposed portions ofthe bottom, aft ofthe bow, from" en'- tering and building up inthe channel 3, the vforward portions of theinner walls 21 of thetwo hulls are providedy with extensonsor fins 38 which are of sufficient depth below the normal keel '35, from the bow toI a l'pointV amidship, to remain alwaysv in the water when the-"bows of the two hulls-rise out of the water. f If desired,v instead of making* the bridges 2a, 2b, 2c, and the longitudinal passage 4 of box-y like construction to quarter 'the personneliof the crafttherein,l these portions: and the 'towers I 4',

14a of the superstructure 2 may-be made ofrc'pen truss worli:I` composed 'of ytubular members welded`l together, tocut down wind'resistanceto a minimum, or the bridgea'towers,A etc., may be stri-ram- Y 'lined in any suitable manner lfori-,he same purpose without 'departing from the spirit 'of theinvent'ion'.

It is generally-recognized that in order for a dive lcomloerv to be effective, itmust ily in a straight line 4directly atv its target fori a-,given distance and given time, ytima-'with a structure ofthe kind hereindescribed, which is capable of great speed, rapidchange of coursaandminmum target surface, the possibilities of the-'craftbeing struck 'byfa bomb launched' from such arr atfacking plane'is reducedto a-niinimum.v The s'amevistrue concerning aerial or other torpedo-launching craft which must be pointed at the target and held on the target in :their course for a given period of time'. f In order .to eliminate any building up ofthe sea inthe water'channel 3, which may'develop 'as a i'esultof friction between the water' and the'vertical parallel sidesv 21,"` 21 of the 'hulls lo and il?, it is one of the objects of the present invention to correct such condition by making the channel slightly wider at the stern of the-craft thanfat the bowof 4the craft, as's'hownin Figsf'l and` 8 respectively. may be accomplished insevin .Figs 2 to mskelthe Vernon aan' sides 21; zr of the two hulls at vslightly diverging angles to each other and to the longitudinalcente'r line :c-of the `channel 3, from 'the bow toward the stern ofthe are. provided with water brakes vmaand 4Gb respectively, each of which comprises a broad gate'- like element fitting into `a correspondingly vbroad 'shallowjrecess 4i inthe bottom of thehull, with the under surface of the brake gate normally flusnwith the-under surface of the hull.` f

Each brake gatefis pivoted at y42 to the hull, to be swungl downwardly from the full line position shownin Fig. 2 to the broken line position shown and a, said/brakevgates being independently and selectively operable from one to theother of said extreme positions or to and from.-intermediatelpositions, as desired.

Each brake gate is provided 'with a 'stiffeni'ng n 43 and a pair ofl laterally spaced reinforcing ribs 44 between andvto which are pivota'lly connected the lowerends of `a` pair of toggle-links 45, 45, the upper ends of which are pivotallyconnectedt to'fa -pair of horizontally slidable toggle rodsM.: f l

-The rods 4S`are slidably mounted `inbearings 41,41 formedin the opposite end walls 48, 48 of a Sea-tight'well` 49 which `communicates with `the b rake gate recess 4I and houses the toggle linkagefby which'thebrake gates are operated. yThe toggle rodsv46 are connected to` ar cross head 50' to which is also connected one end of a hydraulic or pneumatic ram or piston rod 5I loperable by a piston in a cylindery 52, which `is secured in xedposition in' thehull la or Ib, vas the case maybe.` fi

Assuming vthat #the lcraft'isvtraveling 'in a straight-line', 'at -high speed, directly at a' target, andthat it discharges oneormore torpedoes from l its tubes 22a,22b, it" maybe desirable' to check thefspeed of the craft abruptly to avoid collision with the target. This is accomplished by operating both water `brakegates 40a, `4llbinto their broken 4line positions simultaneously.- Obviously the speed'of thedrivingxpropellers1,'.1a and 1b would Vbe reduced accordingly, at the same time.

The `above 'method-can also be employed eiliciently tc suddenlyscheck the speedof thecraft to avoid a Atorpedo discharged by an enemy and which was fired at' a'llead calculated, at thespeed 'the'fcrafti had been' traveling, to :make contact With thecrafttat a predeterminedpoint ofintersection of the line oftravel of the craftfand the yline of'ltravel of the projectile. Thus, byslowing up the craft abruptly the projectile Iwill be avoided-M.' i l In addition to the above,.the craft, while` traveling at highfspee'd' may be causedto turn sharply to port or starboard by operatingbut `one or the other of the water brakes 40a or Mib, at the-same time as the ruddersl Scand 8b are swung to effect such a turn. i .The resistance to the forward progress of the` onehull,` as providedby the depressed water brake thereon, will cause the other hull to swing sharply in; an--arc ofwhich `the depressed brakefwould constitute the center, or substantially sc.4 'w i r Obviouslythe ,water -brake gates, the rudders, the propellers etc., are operated, through any laterally spaced hulls with a channel therebetween, a plurality of bridgegstructures spanning said channel at spaced intervals along said hulls for maintaining said hulls insaid spaced relation, and a plurality of independentflaterally spaced aircraft runways extending longitudinally of said hulls on top of said bridge structures.

2'. An aircraft carrier, comprising a pair of laterally spaced hulls with a'channel' therebetween, a plurality of bridge structures spanning said channel at spaced intervals along said hulls for maintaining said hulls in said spaced relation,

a plurality of independent laterally spaced aircraft runways of uniform predetermined widths respectively extending longitudinally of said hulls on the top side of said bridge structures, and a landing deck of relatively greater width than each runway for aircraft adjacent theA stern of the carrier and communicating with eachrunway.

3. An aircraft carrier, comprising a pair of laterally spaced' hulls with a channel therebee tween, a plurality of bridge structuresspanning said channel at spaced intervals along said hulls for maintaining said hulls in said spaced relation, a plurality of independent laterally spaced aircraft runways of uniform predetermined widths respectively extending longitudinally of said hulls on top of said bridge structures, a landing deck of relatively greater width than each runway for and communicating with each runway at the stern of the carrier, and catwalks along the sides of the runways adjacent the landing decks thereof.

4. An aircraft carrier, comprising a pair of decked laterally spaced hulls with a channel therebetween, a plurality of bridge structures spanningsaid channel at spaced intervals along said hulls for maintaining' said hulls lin said spaced relation, a plurality of independent laterally spaced aircraft runways extending longitudinally of and respectively situated above said hulls on top of said bridge structures, and storage areas for aircraft on lthe decks of said hulls be-r neath the outermost of'said independent runways intermediate successive bridge structures. 5. An aircraft carrier, comprising a pair of decked laterally spaced hulls with a channel therebetween, a plurality of bridge structures spanning said channel at spaced intervals along said hulls for maintaining saidvhulls in said spacedrelation, a plurality yof independent laterallyspaced aircraft runways extending longitudinally of and respectively situated above said hulls on top of said bridge structures, storage areas for aircraft on thev decks of lsaidl'iulls beneath theoutermost of said independent runways intermediate successive Qbridge structuresl and means for transferring. aircraft from said outermost storage spaces to said runways respectively and vice versa. y

6..An aircraft carrier comprising a pair of laterally spaced hulls with a rchannel therebetween,.a plurality of bridge structures spanning said channel at spaced intervalsalong said hulls for maintainingsaid hulls in said spaced relation,

'a longitudinally extending aircraft hanger support carried by theundersides of said` bridge structures above said channel. and means for hoisting aircraft yfrom the water in said channel to said support.

7. An aircraft carrier comprising a pair of laterally spaced connected hulls,-inc1uding substantially flat vertical inner sides forminga free-A unobstructed channel therebetween, laterallyv .spaced outer sides curving inwardly toward and joining with said at vertical innersides in the planes of the latter to form the bows of said hulls 

